I have a air handler outside. Both ac and heat which is common in NC . We woke up and the
Thermostat is blank. I have checked but don't see any thrown switches. The unit is 11 year old
And I don't see a way to check for a battery the numbr I got off the panels was bryant 960-15500012-00001

Any chance you had a weather event last night that may have interrupted power or possibly blown a 5 amp fuse in the air handler?

Unless your thermostat is very old it should have a battery(s) in the back of it that could be replaced. The thermostat face should just pop off or rock off one way or another.

The thermostat is powered by 24v and that comes from a transformer that steps down the 240v at the unit. The transformer is located in the air handler as well as the above mentioned (usually) 5 amp fuse. You may find your culprit there. Otherwise your unit is probably just fine other than just getting power back to your thermostat to control it.

Good luck